Note 1: it's not necessary to put SLA monitors on both, but wanted to show it in case anyone seeing this has more than 2 connections, it's pretty easy to figure out how to configure the ASA for an arbitrary number of connections.
Note 2: The only harm in configuring as many monitors as you have WAN connections, if both connections go down there would be no default route, which is a problem if you use "far" monitoring targets. The example uses Google's DNS servers, which are not on the local links. If you used the DG of the link then the target is always local; this has the trade-off of a connection being considered "up" even if there are problems upstream of your connection...

TL;DR ASAs can not do load-balancing across multiple WAN connections. The only support redundancy. There are other devices available that can do load-balancing of course...